Currently, the cooper-tube-fin type (tube-fin type) heat exchanger occupies a leading role in the field of refrigeration technique since it has a simple machining technology and a low cost. The tube-fin type heat exchanger generally includes circular tubes and various types of fins, the tubes and fins are connected by a tube expander, thus the thermal contact resistance is large, and the heat exchanging coefficient is low, and the tubes are tend to move with respect to the fins, which may gradually enlarge holes in ribs, and further reduces the heat exchanging efficiency and shortens the service life. The micro-channel heat exchanger as a new-type, high-efficient and compact heat exchanger becomes a research hotspot at present and has already been applied in automotive air-conditioners and large commercial central air-conditioners.
FIG. 1 shows the structural principle of a conventional micro-channel refrigeration system. As shown in the Figure, the refrigeration system mainly includes a compressor 1′, a condenser 2′, a throttling device 3′ and an evaporator 4′. The condenser 2′ and the evaporator 4′ each functions as a micro-channel heat exchanger and each mainly includes flat tubes, fins and manifolds. An ideal heat exchanging effect may be realized by using the micro-channel heat exchanger as the condenser, however when the micro-channel heat exchanger is used as the condenser, a non-uniform distribution of refrigerant may occur, which greatly decreases the heat exchanging performance of the heat exchanger. An existing solution to the above issue is described by taking the micro-channel evaporator 4′ as an example, as shown in FIG. 2, the micro-channel evaporator 4′ mainly includes two manifolds, including an inlet manifold 41′ and an outlet manifold 42′ which are configured to distribute and collect the refrigerant. Flat tubes 43′ are regularly arranged between the two manifolds. Corrugated or louver-shaped fins 44′ are provided between adjacent micro-channel flat tubes, to improve the heat exchanging efficiency between the heat exchanger and the air. For ensuring that the refrigerant in the micro-channel evaporator 4′ can be uniformly distributed into each flat tube 43′, a distribution pipe 5′ with a sealed end is inserted into the manifold 41′, and holes 51′ or grooves are formed at intervals on a wall of the distribution pipe 5′ in the length direction, thus via these holes 51′ or grooves, the refrigerant can be uniformly distributed into each flat tube 43′ for circulation.
In the case that the micro-channel heat exchanger is used as the evaporator, the distribution pipe for optimizing the distribution of the refrigerant needs to be provided at an inlet of the evaporator, and the quality of the distribution pipe directly affects the distribution of the refrigerant, thus the difficulty of manufacturing technique, and economic and time costs are bound to be increased. Especially for the household appliance industry, the time and economic costs for optimizing and manufacturing the distribution device occupy a very high proportion.
Besides, due to many influence factors, under different kinds of working conditions, each heat exchanger is required to perform the optimizing process of the distribution pipe, so as to effectively utilizing the heat exchanging area of the micro-channel heat exchanger, however the optimizing process may take a large amount of time, and also increases the difficulty of manufacturing technique.